Conventional radiographic and fluoroscopic (R&F) X-ray systems usually comprise a tiltable X-ray table upon which a subject under examination is placed, an imaging system used to convert the X-radiation into visible light images, a viewing device used to display the light images and a spotfilmer used for making a film record of the viewed image.
In tiltable type X-ray tables a flat topped elongated table body is pivotally connected to a base or pedestal so that it can be tilted in either direction from its normal position in which the patient-supporting top surface is horizontal. The table body pivots about an axis parallel to its top and perpendicular to its length. In so-called 90/90 tables, the table body is tiltable in either direction 90.degree. from the horizontal. The tilting permits examination of the patient in any angular position between these two extremes. Other tables have a body which is tiltable in one direction from the horizontal to a vertical position and in the other direction to a so-called Trendelenburg position wherein the angle of the table top is angularly placed approximately 15.degree. past the horizontal. X-ray tables of this type are well known.
Such tables typically include a tower assembly which is movably carried by the table body. The tower assembly is carried by a carriage in a path transverse to the longitudinal extent of the table body. The carriage is longitudinally movable relative to the table body along two rails mounted in the table body. The X-ray source is mounted to the carriage and is housed in the table body. The tower assembly movably supports radiation sensing devices such as a spotfilmer and imaging system. The radiation sensing devices are movable with respect to the tower assembly in a vertical direction. The imaging system typically includes an image intensifier tube and associated cameras for viewing the image intensifier tube output. In other prior art systems a fluoroscopic screen may be used in lieu of the imaging system.
The spotfilmer is commonly supported by the tower assembly in spaced relation above a patient examining surface defined by the X-ray table top and in alignment with the X-ray source. The combination of the carriage and tower assembly permit the spotfilmer to move in the transverse, longitudinal and vertical directions with respect to the table body. The X-ray source is mounted to the carriage such that the longitudinal alignment of the source with the radiation sensing devices is maintained during movement along the entire table body length. An example of one such tiltable X-ray table can be found in U.S. Pat. No. 4,197,465 issued to Schneider and owned by the present assignee and which is expressly incorporated herein by reference.
The three rectilinear paths of travel permit the spotfilmer/imaging system combination to be moved to any selected position over the table top and to any selected distance from the top within the limits of the respective paths of travel.
Since the movement of the spotfilmer/imaging system combination relative to the tower is vertical when the table top is horizontal, counterbalancing weights are carried in the tower to facilitate the vertical movement of the spotfilmer.
Since the spotfilmer/imaging system combination is movable in a vertical path when the table top is in a vertical position, weights to counterbalance the combination are provided in the table body.
In a prior art counterbalancing system, for every one pound of spotfilmer/imaging system weight, an additional 11/2 pounds of counterbalance weight is required. An example of one such counterbalancing system can be found in U.S. Pat. No. 3,916,203 issued to Norgren and owned by the present assignee and which is hereby expressly incorporated by reference.
Prior art spotfilmers generally include a cassette carriage assembly movably supported within the spotfilmer housing. The cassette carriage assembly serves as a means for supporting and conveying an X-ray film cassette to one of a plurality of positions within the housing. The housing also supports an operator control and function display panel which is mounted across the front of the spotfilmer. One or more operating handles are also provided to manually move the spotfilmer in the longitudinal, vertical and transverse directions with respect to the patient support and alternatively may include one or more sensors for activating a power drive system to facilitate the positioning of the spotfilmer by the operator. The control and function display panel include a plurality of indicators and soft touch push-buttons. The indicators inform the operator of the status of various spotfilmer functions and formats. The pushbuttons are used for selecting film formats, film cassette positioning, table base and top movements, exposure initiation, X-ray field size and various other spotfilmer functions. An example of one such spotfilmer can be found in U.S. Pat. No. 4,357,538 issued to Hunt et al. and owned by the present assignee and which is hereby expressly incorporated by reference.
As noted above, R&F systems are operated in either a fluoroscopic or radiographic mode. In the fluoroscopic mode the spotfilmer and the associated imaging system is positioned over the patient and the X-ray source is energized. X-rays propogate along a path traversing the patient support and penetrate the patient. Radiation emerging from the patient impinge upon a radiation sensor. Such sensor may include a fluoroscopic screen mounted to the spotfilmer housing or, more typically, upon an image intensifier tube mounted on top of the spotfilmer housing in alignment with the X-ray source. The image intensifier tube is either coupled to a mirror optics system (described in more detail below) which permits direct viewing of the output of the image intensifier tube or is coupled through a television camera to a CRT display monitor which translates the impinging X-ray pattern into a video image. An example of one such imaging system can be found in U.S. Pat. No. 4,193,089 issued to Brougham et al. and owned by the present assignee which is hereby expressly incorporated by reference.
If the operator desires a film record of the area being examined and viewed fluoroscopically, a radiographic mode is selected. In this mode, a film cassette is positioned within the spotfilmer housing in alignment with the patient area being examined. The X-ray source is then energized to expose the X-ray film.
In prior art R&F systems which utilize a CRT display monitor, the monitor and associated electronics is of such size and weight that it is mounted and enclosed in its own housing assembly. In order to provide flexibility in positioning, the monitor assembly is mounted on movable support means such as roll cart or an overhead support assembly. These mounting means allow the display to be brought in relative close proximity to the table without interfering with table movements, patient positioning or movement of attending personnel. As such, the monitor is usually off to one side of the table base and positioned some distance away from one viewing the image displayed on the CRT. The placement of the monitor in this fashion forces the operator to divide his or her attention between the patient under examination, spotfilmer controls, function displays and the monitor thereby reducing operation efficiency and causing operator inconvenience.
Mounting the CRT display for movement along with the spotfilmer/imaging system combination while possible, has been impracticable due to their excessive size and weight. A conventional CRT requires 14"-19" in depth for mounting and weigh 17-25 pounds. With the image intensifier tube and associated cameras mounted on the spotfilmer, the depth dimension of the CRT would require mounting in such a fashion that the front face would be hyperextended beyond the control deck of the spotfilmer. Twenty-five to thirty-seven (25-37) pounds of additional counterweights would also be required to offset the added weight of the CRT. The added weight would place additional stress on the tower assembly and would reduce the maneuverability of the spotfilmer.
The prior art systems employing a fluoroscopic screen as the viewing device suffer from disadvantages in that the screen must be mounted perpendicular to the central axis of the X-ray beam. Since the perpendicularity must be maintained for proper image focus, the screen cannot be adjusted for a comfortable viewing position. Mounting in this manner presents a practical limitation to viewing the patient under examination in that the patient must be in an upright or vertical position in order for the radiologist to see the image in its proper orientation. In order to adequately view a fluoroscopic screen image, the room lighting must be subdued so that one viewing the image can become "dark adapted." The radiation intensities required for this type of system are also higher.
A mirror optics viewing system may be mounted to the spotfilmer housing and in optical alignment with the output of the image intensifier tube thus eliminating the television camera and associated monitor. Through a series of mirrors and lenses the image produced at the output of the image intensifier tube is magnified, focused and reflected onto a viewing mirror which is adjustable for the convenience of the operator. An example of one such mirror optics viewing system can be found in U.S. Pat. No. 3,018,375 issued to Graves et al. and owned by the present assignee and is hereby expressly incorporated by reference. A disadvantage to such a system is that the viewed image is minified in relation to the object under examination. Further, the image must be viewed in a darkened room and only one person can conveniently view the image at a time. Also, due to the limited field of view of the optics chain, the person viewing the image must keep his or her line of sight substantially stationary. In systems that employ radiation control means known as Automatic Brightness Control, the mirror optic viewing system suffers a further disadvantage in that variations in room lighting may be fed back into the brightness control and may cause variation in radiation intensity.
The present invention contemplates a new and improved display for radiation imaging which overcomes the above referenced problems and disadvantages.